Optimal foraging and community structure: implications for a guild of generalist grassland herbivores

Abstract

A particular linear programming model is constructed to predict the diets of each of 14 species of generalist herbivores at the National Bison Range, Montana. The herbivores have body masses ranging over seven orders of magnitude and belonging to two major taxa: insects and mammals. The linear programming model has three feeding constraints: digestive capacity, feeding time and energy requirements. A foraging strategy that maximizes daily energy intake agrees very well with the observed diets. Body size appears to be an underlying determinant of the foraging parameters leading to diet selection. Species that possess digestive capacity and feeding time constraints which approach each other in magnitude have the most generalized diets. The degree that the linear programming models change their diet predictions with a given percent change in parameter values (sensitivity) may reflect the observed ability of the species to vary their diets. In particular, the species which show the most diet variability are those whose diets tend to be balanced between monocots and dicots. The community-ecological parameters of herbivore body-size ranges and species number can possibly be related to foraging behavior.

Activity budgets and foraging behavior of bison on seeded pastures

“…Although bison are roughage grazers adapted to low quality forage, they are selective when conditions allow (Peden et al 1974, Belovsky 1986, Plumb and Dodd 1993, Coppedge et al 1998. Bison (this study) consistently consumed the upper portion of the plant.…”

Do endogenous seasonal cycles of food intake influence foraging behaviour and intake by grazing sheep?

“…These constraints may be imposed by factors that are largely internal to the animal, such as food requirements, limited capacity for digestive processing and daily foraging time. They may also be due to interactions between plant and animal factors, such as rates of encounter with and consumption of plants (Belovsky 1986;Spalinger & Hobbs 1992;Owen-Smith 1993). Despite their theoretical importance, very little is known about the relative positions of these internal and environmental constraints.…”

Control of energy balance by a wild ungulate, the kudu (Tragelaphus strepsiceros) through adaptive foraging behaviour

“…Foraging models formulated for herbivores have extended the simple models originally developed for predators by including multiple constraints, specifically those of maximum eating rate, thermal influences on foraging time, and digestive-processing limitations (Belovsky, 1978(Belovsky, , 1986Owen-Smith & Novellie, 1982;Verlinden & Wiley, 1989). However, they have not incorporated constraints arising from metabolic-processing capacity.…”